21534200729 has 4 divisors (see below), whose sum is σ = 21535592976. Its totient is φ = 21532808484.

The previous prime is 21534200659. The next prime is 21534200759. The reversal of 21534200729 is 92700243512.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21534200729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21534200759) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 672659 + ... + 703944.

It is an arithmetic number, because the mean of its divisors is an integer number (5383898244).

Almost surely, 2^21534200729 is an apocalyptic number.

It is an amenable number.

21534200729 is a deficient number, since it is larger than the sum of its proper divisors (1392247).

21534200729 is a wasteful number, since it uses less digits than its factorization.

21534200729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1392246.

The product of its (nonzero) digits is 30240, while the sum is 35.

The spelling of 21534200729 in words is "twenty-one billion, five hundred thirty-four million, two hundred thousand, seven hundred twenty-nine".